Aircraft Materials Lighten Up

Load-bearing structures can be reinforced with rigid PU (polyurethane) structural foams, such as BASF's Elasturan and Elastocast, allowing the downgauging of metal wall thickness. "In load floor examples from another transportation segment, overall weight reduction can be up to 50 percent compared to metal, while also improving strength and stiffness," said Mark Mielke, senior manager, aerospace, at BASF.

A primary lightweighting material in structures and interiors is metallic and non-metallic honeycombs. Hexcel's honeycombs are now being adapted to also address noise dampening blankets around aircraft engines due to more stringent noise constraints, said Imad Atallah, group product manager for core honeycomb, at Hexcel.

The company's Acousti-Cap technology is a single-cell, single-layer acoustic treatment on one side of a honeycomb core structure, which has a single resistance value. Clark Smith, Hexcel's research and technology manager for core and panels, said:

We join pieces of the honeycomb core together with a thin seam, not a joint, so it's acoustically invisible. We insert a cap material into the honeycomb core, cell by cell. Then we stabilize it by doing a precision dip into a resin, to keep the cap in the cell.

In the next couple of years, Hexcel will introduce a more customized single-cell treatment that lets each cell be treated differently, modifying sound resistance values by how many caps with different resistant values and heights are in each cell.

Alcoa's aluminum-lithium alloys reduce weight for structural components, such as this stretch-formed fuselage panel for a single aisle airplane, developed by Alcoa and Spirit AeroSystems for the 2011 Paris Air Show. (Source: Alcoa)

Other lightweighting methods include 3M's glass bubbles for rubber and plastic interior parts. They reduce filled plastic parts' weight by 10 percent to 20 percent and also improve dimensional stability compared to glass fibers, said Louis J. Lundberg, global business manager for specialty additives in 3M's energy and advanced materials division. Its newest iM16K filler product for polypropylene and polyamide also reduces cycle times by 15 to 25 percent.

REHAU, which produces polymeric parts and makes polymer-based materials for plastic extrusions used in aircraft cabin components, has developed RAU-Flight, a low-density polyphenylsulfone (PPSU) or polyetherimide (PEI) material. It incorporates an earlier 3M glass bubble product, iM30K, with a crush strength of 28,000 psi. Bernd Kupferer, REHAU's business unit manager for industrial solutions, said that a single handrail system for an Airbus A320 made of RAU-Flight could reduce the weight of an aircraft by more than 5kg.

Very comprehensive overview of the state of materials exploration in the aerospace industry. It was interesting to me that companies don't see composites as the be-all, end-all solution--a surprise given that so much attention and hype is focused on their deployment. I was also pleased to see that companies are keeping somewhat of a watchful eye on sustainability concerns as they vet out these new materials.

Beth, I also found it enlightening to discover the mix of materials being developed for, and used in, in bleeding-edge aircraft design. But composites are, in fact, a big part of all this, so it's not all hype. It was a big surprise, and encouraging, to see that sustainability concerns are finally reaching and influencing this industry, like so many others.

I saw no mention of cellular steel (superalloy) products. Inside and near turbine engines, the temperatures are too high for most of the materials mentioned. In fact the temperatures seem to be rising, to the point that many parts that were traditionally made of titanium alloys are failing. For quite a few years, we've been working both on traditional superalloy honeycomb and on other brazed cellular structures that can replace titanium and withstand much higher temperatures, and yet be weight-neutral or even weight-saving.

CPDick, thanks for that information. We focused on structural and interior component materials for this feature, not engines, but that's good input. It's especially interesting that temperatures are outpacing titanium. Can you give us your company name for possible followup?

I just looked, and realized that the non-honeycomb sandwich products are not yet shown on our website. We have a number of such products that we have been developing and testing with major aerospace companies for quite a few years, and are just about to start producing our first full-scale product samples.

sometimes new ideas generate new discovweries, consider a study of all species of bird feathers and the incredible design weight, lift, etc etc, flexible wings to use both mechanical power and atmospheric changes , perhaps the ultra lights culd take on a new perspective> my wing collection has some very old feathers that have not changed over time as I keep studing these designs which are incredible' I think there is legislation forbading feather collections, but I have a deep native american background, the race card and holocaust is not in my deck. My spirit remembers the genocide of americas 20,000 tribes, and the role buffalo soldiers played when freed. I worked for a time at LTV Aerospace in the 60's on the A-7 series, while no bird is powered with fuel they can indeed do some pretty tricky stunts, like gliding for hours, with small wing shifts , in acord with atmospheric variables, fins do compensate to keep on course, but consideration of actual feathers may be in our future. whatever. Birds of prey do reach considerable speed, without any fuel at all,

Many of the new adhesives we're featuring in this slideshow are for use in automotive and other transportation applications. The rest of these new products are for a wide variety of applications including aviation, aerospace, electrical motors, electronics, industrial, and semiconductors.

A Columbia University team working on molecular-scale nano-robots with moving parts has run into wear-and-tear issues. They've become the first team to observe in detail and quantify this process, and are devising coping strategies by observing how living cells prevent aging.

Many of the new materials on display at MD&M West were developed to be strong, tough replacements for metal parts in different kinds of medical equipment: IV poles, connectors for medical devices, medical device trays, and torque-applying instruments for orthopedic surgery. Others are made for close contact with patients.

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